Tears play an important part in eye health and general comfort, but because they’re “invisible”, people don’t appreciate just how much we depend on them until something goes wrong with the flow. Dry eyes can be extremely uncomfortable, because the main role of tears is keeping the cornea (the thin transparent windows into the eye) moist, and supplied with oxygen and nutrition. The cornea is the most sensitive area of the whole outer body, and this makes any disturbance extremely uncomfortable, capable of completely disrupting normal behavior until it’s fixed.
Why dry eyes is a problem no one talks about
Dry eye relief is often discussed as a problem of tear quantity, but that concept misses a key part of the condition. In many people, the eyes may still produce tears, yet those tears fail to stay on the eye long enough to do their job.
This happens because dry eyes are not always caused by low tear production. In a large number of cases, tears evaporate too quickly, leaving the surface of the eye exposed between blinks.
The multi-function teardrop
The tear film is not just water. It is a complex, layered structure that performs several essential functions at the same time.
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- Lubricating the surface of the eye.
- Cleansing away dust and debris.
- Feeding the cells of the cornea, which has no blood supply.
- Delivering oxygen needed for normal corneal metabolism.
Natural tears are made up of three coordinated layers.
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- The aqueous layer, produced by the lacrimal glands, forms the bulk of the tear film and keeps the eye hydrated while supplying oxygen and nutrients.
- The oil layer, produced by the Meibomian glands, forms the outer surface of the tear film and slows tear evaporation.
- The mucus layer, produced by conjunctival goblet cells, anchors the tear film to the cornea and helps it spread evenly.
Electrolytes such as sodium, potassium, and calcium are also present, supporting normal cell function on the eye’s surface.
How tears work
The National Eye Institute provides an excellent explanation of how the surface of the eye is protected by these layers working together as a single unit. When the outer oil layer becomes thin or uneven, moisture escapes quickly.
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- The eyes may start to feel gritty or rough.
- Blinking can become uncomfortable.
- Irritation increases between blinks.
- Rubbing the eyes may feel instinctive but usually makes symptoms worse and can actually damage the cornea.
Why the modern environment and lifestyles make tear evaporation worse
Rates of dry eye have risen as modern habits place new demands on the tear film. Many of these factors increase tear evaporation rather than reducing tear production.
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- Extended screen time, which reduces blink frequency.
- Air conditioning and indoor heating that lower ambient humidity.
- Contact lens use, which can disrupt tear stability on the cornea.
- Age-related changes that alter tear composition.
In evaporative forms of dry eye, including evaporative dry eye, the oil layer becomes less effective at sealing in moisture.
Why adding moisture isn’t always enough
Many over-the-counter eye drops focus on adding liquid to the eye’s surface. While this can feel soothing at first, the relief is often short-lived if evaporation is not addressed.
Without protection, added moisture may disappear within minutes. This explains why some people find themselves reapplying drops frequently without lasting improvement.
A different way to think about dry eye relief
Supplementing tear volume provides temporary relief, but the underlying problem is still there, so a solution that stops it from recurring makes more sense. Instead of replacing tears, protect what’s already there.
Stabilizing the tear film allows natural moisture to remain on the eye longer. This shifts the focus of dry eye relief from replacement to preservation.
Perfluorohexyloctane eye drops work by forming a smooth, protective layer over the eye’s surface.
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- The layer reduces tear evaporation.
- Moisture lasts longer between blinks.
- The approach is particularly suited to evaporative dry eye.
More specific information about perfluorohexyloctane can be found on the Federal Government’s National Library of Medicine’s website.
Perfluorohexyloctane is the generic component, sold under different brand names
In the United States, perfluorohexyloctane eye drops are sold under the brand name Miebo. The product is designed to provide relief without preservatives.
Internationally, the same compound is marketed as EvoTears or Hycosan Shield, and in some countries may require a prescription.
The main benefits of Miebo, EvoTears, and Hycosan Shield
These products are designed to support tear film stability rather than simply adding fluid.
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- Useful for people with heavy screen exposure.
- Compatible with contact lens wear, when used as directed.
- Helpful for burning, gritty, or irritated eyes.
- Suitable when other drops provide only temporary relief.
What to know about tear evaporation before trying Miebo
Products that reduce evaporation do not address underlying causes of dry eye. Persistent or worsening symptoms should always be discussed with a qualified healthcare professional.
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- Follow instructions on frequency and dosing.
- Use only as directed.
- Remove contact lenses if required.
- Seek medical advice if symptoms continue.
Takeaway thoughts: eyes are the windows to the world
Dry eye is not always a lack of moisture. In many cases, it is a problem of protection.
Understanding the role of evaporation changes how relief is approached and why some solutions work better than others.
Frequently asked questions about tear evaporation
What causes tears to evaporate too quickly?
Tears evaporate quickly when the outer oil layer of the tear film becomes thin or uneven. This can happen with age, prolonged screen use, dry indoor air, or dysfunction of the oil-producing glands in the eyelids.
Is evaporative dry eye different from other types?
Yes. Evaporative dry eye occurs when tears are present but do not remain on the eye long enough. Other forms are related to reduced tear production.
Why do screens make dry eye worse?
Screen use reduces blink frequency. Fewer blinks allow moisture to escape from the eye’s surface, increasing evaporation.
Are preservative-free drops important?
Preservatives can irritate sensitive eyes when used frequently. Products designed for relief without preservatives may be better tolerated.
Does reducing tear evaporation cure dry eye?
No. Reducing evaporation can improve comfort, but it does not cure underlying conditions. Medical evaluation is important if symptoms persist.
